The invention relates to a method and composition of matter for removing organic contaminants from fluids, such as liquids, gases, or the like, and is particularly suitable for decontaminating water, air, and soil.
There are increasing volumes of organic liquids that are used throughout the world in the form of fuels, lubricants, chemicals, food additives, and the like which contaminate the air, water and soil. The practices of burying organic materials, dumping waste products at sea, venting effluent gases to the atmosphere, filling automobiles with gasoline, disposing of spent fuels, and the like, for the last fifty years have created dangerous levels of contamination in both isolated and populated areas. Oil refineries continuously emit hydrocarbon vapors to the air, and oil spills at sea and accidents on land have taken a substantial environmental toll.
A variety of techniques, and variety of proposals, have been used and made in the past for cleaning up or containing contaminants. For example, diatomaceous earth (e.g. kitty litter) has been used to absorb small spills in garages, manufacturing plants, and commercial operations. Mats have been fabricated from polyolefin fibers, such as polypropylene, and have been used to pick up crude spills from water. Booms have been used to contain spills so that beaches and natural habitats are not endangered. Alsoxe2x80x94such as shown in U.S. Pat. No. 4,941,978xe2x80x94granulated elastomeric gums (such as block copolymers of ethylenelbutylene and styrene) have been used to absorb oil spills.
The techniques utilized in, and contemplated by, in prior art have had varying degrees of effectiveness and versatility. Where large volumes of contaminated fluid are to be treated, there are oftentimes difficulties in the treatment material clumping up, or congealing, causing clogging of the treatment vessel or column.
According to the present invention a method of removing organic contaminants from contaminated liquid, gas, soil, or mixtures thereof is provided, as well as a discrete non-clumping mechanically stable geometric alloyed material shape, which is relatively simple to practice or manufacture, versatile, and effective. The shapes produced according to the present invention are non-clumping and mechanically stable, and are capable of removing at least about 90% of the contaminants in a first pass of contaminated fluid through a column of the shapes.
The method of the present invention is used in the direct removal of organic and bacterial contaminants from waste streams of water, oil, soil and mixtures thereof. Typically the waste stream is passed through an ozone generator which removes bacterial and heavy oil contaminants, followed by passing the stream through a fixed bed of organic polymer which sorbs all of the residual organic contaminant. The organic polymer is a polymer blend of a thermoplastic polymer such as a polystyrene, a copolymer of polystyrene/butadiene, and a filler (salt) such as a magnesium oxide. The organic polymer blend is a thermoplastic composition that can be formed in stable geometric shapes which enhance absorption of organic contaminants, such as spherical foamed particles of between 0.02-0.125 inches in diameter, or discs having a maximum dimension of about 0.5 cm, and a thickness of about 0.01-6 mm.
The polymer material readily sorbs and holds organic vapors and liquids. Further, the specific compositions according to the invention have increased mechanical stability compared to the prior art, so as to not collapse or congeal (clump) during the sorption process. The compositions of the invention have reduced costs as polymer blends, they can be fabricated into different desired specific geometries, they sorb hydrocarbons quickly, and they have high sorption levels.
According to one aspect of the present invention a method of removing organic contaminants from contaminated liquid, gas, soil, or mixtures thereof is provided which comprises the following steps: (a) Producing discrete non-clumping mechanically stable geometric shapes of a blend of elastomeric material with about 5-45% by weight thermoplastic polymer. (b) Providing the shapes in a loose form or packing, And, (c) bringing a fluid containing organic contaminants into contact with the shapes in loose form or packing so that the shapes absorb organic contaminants from the fluid.
Step (a) is preferably practiced by blending and alloying as an elastomeric material polystyrene-butadiene copolymers, polystyrene-butadiene-polystyrene triblock copolymers, polystyrene-isoprene-polystyrene triblock copolymers, polystyrene grafts of elastomers, or mixtures thereof with about 5-45% by weight as the thermoplastic polymer polystyrene, a polyolefin, or mixtures thereof. Step (a) is typically also further practiced by blending and alloying about 4-12% by weight of a filler (typically MgO, although other carbonates, oxides or hydroxides of calcium or magnesium can be used, as well as talc, silica, diatomaceous earth, or mixtures thereof) with the elastomeric material and thermoplastic polymer. Typically about 0.1-10% (e.g. 0.5-2%) foaming agent is used with the material to produce foamed shapes.
Typically the method includes the further step, prior to step (c), of passing the contaminated fluid through an ozone generator. Step (b) is typically practiced by forming a column of geometric shapes and passing a stream of contaminated fluid through the column. Once the geometric shapes in the column become saturated with organic contaminant, they are replaced.
Step (a) may be practiced to produce disc shaped geometric shapes having a maximum dimension of about 0.5 centimeters and a thickness of about 0.01-6 millimeters. Alternatively, step (a) may be practiced to produce spherical shapes having a diameter of less than about 1.25 inches (e.g. between about 0.02-0.125 inches). Step (b) is typically practiced so as to remove at least about 90% of the contaminants in a first pass of the contaminated fluid through the column.
Where soil is contaminated, there may be the further steps of flooding the contaminated soil with water and retrieving the water. Then step (c) is practiced by passing the retrieved water through the column.
The invention also relates to a discrete non-clumping mechanically stable geometric alloyed material shape. The shape consists essentially of about 55-95% by weight thermoplastic elastomer, about 5-45% thermoplastic polymer, and about 0-12% filler. Preferably about 4-12% filler and about 6-25% thermoplastic polymer are utilized. The shape may be foamed (e.g. by using about 0.1-10% by weight foaming agent).
The shape according to the invention is preferably spherical with a maximum diameter of about 1.25 inches, or a circular disc having a thickness of about 0.1-6 millimeters. When foamed, the shapes typically have a closed cell foam construction. The fillers, elastomeric material, and thermoplastic polymer that may be utilized are as described above.
It is the primary object of the present invention to provide a method of removing organic contaminants from contaminated fluids in an effective manner, and discrete shapes which may be cost effectively produced and are well suited for use in the method of the invention. This and other objects of the invention will become clear from an inspection of the detailed description of the invention, and from the appended claims.